The Major Transitions in Evolution

John Maynard Smith + Eörs Szathmáry

A survey of the "key events" in evolution by two leading theorists,
The Major Transitions in Evolution ranges all the way from prebiotic
chemistry through to the origins of society. As a result it is both
scattered (though there are some themes that recur throughout) and shallow
(though it tends to assume background knowledge and to start straight in
on the most interesting topics). There is some fascinating material in
Major Transitions and serious students of evolution won't want to miss
it, but I would recommend more focused alternatives first, perhaps (from
recent reading) Gerhart and Kirschner's Cells, Embryos, and Evolution,
Carroll's Patterns and Processes in Vertebrate Evolution, or Dyson's
Origins of Life.

The authors, good reductionists both, naturally start at the bottom
and work their way up. A brief discussion of general concepts such as
progress, complexity, and transition leads naturally into the question of
what life is and a glance at non-living systems that approach it in some
ways (the Oklo reactor and the chemoton). They then offer a potpourri
of prebiotic chemistry (diversity without replication, the Miller-Urey
experiment, surface metabolism, extraterrestrial organic chemistry)
and mathematical models (replication accuracy and error thresholds,
hypercycles and stochastic correctors). This leads to debates about the
primacy of proteins and nucleic acids, and the origins of translation
and the genetic code. (Smith and Szathmáry are obviously supporters of
RNA-world approaches, but they give I think a fair appraisal of theories
of Kauffman and Dyson based on autocatalytic protein networks.)

Then there are chapters on the origins of protocells (membranes,
the negibacterial double membrane, the origin of chromosomes) and of
eukaryotes (mitosis, intracellular membrane systems, mitochondria and
other organelles, centrioles and undilipodia). Next come chapters on
sex (with a little about the nature of species), intragenomic conflict,
and symbiosis. And four chapters cover development: one on simple
organisms (self-assembly and its limits, cell cycles and temporal
differentiation, yeast budding, the alga Volvox, and slime moulds);
one on gene regulation, cell differentiation, and the preconditions for
the metazoa; one on spatial patterns and positional information; and one
on the connections of development with evolution (levels of selection,
gene homologies, zootypes and archetypes). This is all, again, at a very
high level: there is, for example, barely a page on homeobox domains.

There was always going to be something disconcerting about an attempt to
say something meaningful about the origins of societies and the origin of
language in so little space, but the chapters on these topics were not
as simplistic as I had feared they might be. The first moves from the
Prisoner's Dilemma and insect sociality to "the Social Contract game"
— and Rousseau, Plato, Durkheim, and Adam Smith. The second provides
an introduction to basic syntax and then touches on language disorders,
possible protolanguages, and connections of language evolution with
tool use.

Major Transitions is clearly laid out, with a good selection
of diagrams and helpful sectioning, but the amount of whitespace is
actually excessive: not only does every chapter begin on a right-hand
page, forcing many blank pages, but each opens with a table of contents,
simply repeating material from the main table of contents, followed by
yet another blank page. Some of this space could have been used for
an annotated further reading list for each chapter, which would have
made the book much more useful as a starting point for more
specialised study.